Effect Of Fluorine And Aluminum On Rat Offsprings’ Learning And Memory Abilities And Amino Acid Neurotransmitters And Acetyl Choline(Ach)

Objective:To investigate effect of fluorine combined with aluminum exposure from maternal pregnancy and feeding period to the offsprings being adults on the rat offsprings’ spatial learning and memory abilities and amino acid neurotransmitters and acetyl choline(Ach) in hippocampus.Methods: Fifty-four adult rats were randomized into 9 groups, six in each group, female-male ratio was 2:1, exposed by drinking water freely. Pregnant rats from androlepsis 0 day to suckling period over 22 days and their newborn rats from delactation to 60 day age were exposed to Na F and Al Cl3 with concentrations(0, 0),(100, 0),(200, 0),(0, 500),(0, 1000),(100, 500),(100, 1000),(200, 500),(200, 1000)mg/L. Experimental period lasted 90 days, weights were weighed once three weeks. Before killed, physiological development and the neurobehavioral reflection indexes of the rat offsprings were observed, learning and memory ability was tested by the Morris water maze, urine collected lasting 12 hours. After killed, rat offsprings’ brains were kept. Fluorine in urine and brain tested by ion selected electrode method, aluminium in urine and brain tested by inductively coupled plasma atomic emission spectrometry; pathomorphism changes in hippocampus were observed microscopically after HE staining; GABA and ASP in hippocampus were assayed by enzyme-linked immunosorbent assay; Glu and Gly in hippocampus were assayed by automatic amino acid analyzer; the expression levels of Ach E, Ch AT in the hippocampus were observed by immunohistochemistry.Results: 1. The general situation of offspring rats: During the experiment,with the increase of concentration of fluorine and aluminum, the weight of the rat offsprings were reduced. Compared with the control group, except the low fluorine group and low aluminum group(0 weeks),the low fluorine group, low fluorine+low aluminum group and low fluorine+high aluminum group(3 weeks), the low fluorine group(6 weeks), weight of offspring rats from every test group reduced(P<0.05); Comparison between every two groups: weight of offspring rats from the low fluorine+high aluminum group was lower than that from the low fluorine group(0, 6, 9 weeks);weight of offspring rats fromthe high fluorine+high aluminum group was lower than that from the high fluorine group(0, 9 weeks) were reduced(P<0.05). 2. Fluorine and aluminum in urine and brain: Compared with the control group, except the fluorine group, aluminum in urine and brain of offspring rats from the other test groups were elevated; except the aluminum group, florine in urine and brain of offspring rats from the other tested groups were elevated(P<0.05); the higher of fluorine and aluminium exposure dose, the higher of fluorine and aluminum in urine and brain of the rat offsprings. 3. Brain weight coefficient and the pathology results of CA3 area in hippocampus: there was no significant difference in brain weight coefficients from every test group and the control group(P<0.05);with increase of fluorine and aluminium doses, the different degree damage of CA3 area in hippocampus of offspring rats. 4. The physiogenesis and neurobehavior reflection: Compared with the control group, except the low fluorine group, the low aluminum group and low fluorine+aluminum group, time of surface righting reflex and cliff avoidance reflex were significantly prolonged(P<0.05); but teething and eye opening time of offspring rats from every test group had no significantly difference(P<0.05). 5. Spatial learning and memory ability: with increase of fluorine and aluminium doses, there were different degree damages to spatial learning and memory in hippocampus of the rat offsprings from every test group. Compared with the control group, except the low fluorine group, the low aluminum group and the low fluorine+low aluminum group, the escape latency(time of the 1st, 2nd, 3rd day) of the rat offsprings from the other test groups was significantly prolonged(P<0.05); the escape latency(time of the 4th day) of the rat offsprings from every tested group was significantly prolonged(P<0.05); with the change of the training cycle and the increase of concentration of fluorine and aluminum, the escape latency of the rat offsprings was reduced gradually. Compared with the control group, except the low fluorine group, the low fluorine+low aluminum group, the first reaching platform time of the rat offsprings from the other test groups was significantly prolonged(P<0.05),the times across platform was reduced from every tested group(P<0.05);Comparison between groups: the low fluorine+low aluminum group compared with the low fluorine group, the high fluorine+low aluminum group compared with the high fluorine group, the escape latency(time of the 4th day) of the rat offsprings was shortened(P<0.05); the low fluorine+high aluminum group compared with the low fluorine group, the escape latency(time of the 2nd, 3rd, 4th day) of the rat offsprings was prolonged(P<0.05); the high fluorine+high aluminum group compared with the high fluorine group,the escape latency(time of the 2nd, 4th day) of the rat offsprings was prolonged(P<0.05), and the low fluorine+high aluminum group compared with the low fluorine group, the high fluorine+high aluminum group compared with the high fluorine group, the times across platform 2nd, 3rd, 4th was reduced(P<0.05).6. Amino acid neurotransmitter in hippocampus: compared with the control group, contents of Glu and Asp in hippocampus of the rat offsprings from every tested group were less(P<0.05); except the low fluorine + low aluminium group and the low fluorine + high aluminium group, contents of GABA in hippocampus of the other tested groups were elevated(P<0.05);contents of Gly in hippocampus of the groups had no significant difference(P>0.05).Comparison between every two groups: compared with those from the low fluorine group, contents of Glu were elevated and GABA were less in hippocampus of the rat offsprings from the low fluorine+low aluminum group(P<0.05); compared with those from the low fluorine group,contents of Glu and GABA were less in hippocampus of the rat offsprings from the low fluorine+high aluminum group(P<0.05); compared with those from the the high fluorine group, contents of GABA were elevated in hippocampus of the rat offsprings from the high fluorine+low aluminum group(P<0.05); compared with those from the high fluorine group, contents of Glu were less and GABA were elevated in hippocampus of the rat offsprings from the high fluorine+high aluminum group(P<0.05).7. The expression of Ach E, Ch AT in hippocampus: there was no significant difference between integral light density values of Ach E or Ch AT in hippocampus from the control group and those from every test group(P>0.05). 8. Combined effects of fluoride and aluminum: there was no obvious interaction between fluorine and aluminum on physiogenesis and neural reflex time, time of the first reaching platform time, contents of Gly and Asp in hippocampus and expression of Ach E, Ch AT in hippocampus(P>0.05); but there were obvious interactions between fluorine and aluminum on weight(0 weeks) and florine in urine, the escape latency, the times across platform and the content of Glu, GABA in hippocampus(F=8.065, 7.521, 4.961, 9.653, 36.274, P<0.05), except the synergism effects on body weight(0 weeks), the rest effects were antagonism. The higher of the exposure dose of aluminium, the higher the fluorine concentration in urine of the offsprings but the lower the fluorine concentration in brain.Conclusion:1.Exposure of fluorine combined with aluminumfrom maternal pregnancy and feeding period to the offsprings being adults,could reduce spatial learning and memory abilities of the rat offsprings.2. Exposureof fluorine combined with aluminum from maternal pregnancy and feeding period to the offsprings being adults, could reduce the level of excitatory amino acid neurotransmitter Glu and elevate the level of inhibitory amino acid neurotransmitter GABA in hippocampus of the rat offsprings.3. Exposure of fluorine combined with aluminumfrom maternal pregnancy and feeding period to the offsprings being adults, could inhibit growth and developmen of the rat offsprings.4. Under the experimental condition, the combined effects of lower doses of fluorine and aluminum on weight(3,6,9 weeks),the escape latency,the times across platform and the Glu,GABA in hippocampus mainly were mild and limited antagonism, but combined effect types of higher doses or longer exposure time of fluorine and aluminum still remain unclear.